RUI: Quantum State Control for Ultracold Atoms

Advances in quantum sensing, communications, and quantum simulation offer a new way forward for technology, surpassing the limitations of present-day devices. The true advantages of quantum technologies - such as enhanced sensing - can only be realized in systems with a high degree of quantum entanglement. Entanglement is a fundamental property of quantum systems that enables information to be stored across spatially separated quantum systems. This project seeks to understand new ways of controlling these fragile systems, thus making entanglement more useful and robust. The project will achieve this research goal by theoretically exploring new types of measurement models, called ‘weak measurements’ in a variety of physical systems. The project serves the national interest by contributing to the progress of science and the development of new technologies based on quantum many-body physics. This award will provide resources to support several undergraduate research assistants from the diverse student body of San José State University. Undergraduate students will engage with the research aims, building research skills in the theory of atomic, molecular, and optical systems, scientific computing, analytical modeling and data analysis. The predominant approach toward creating highly entangled systems has been isolation: remove all environmental disturbances and protect the system as much as possible. Although successful, this approach is hard to scale up. This research program instead manipulates quantum systems via weak measurement and feedback to engineer new quantum states of ultracold atoms, moving beyond fragile, highly isolated systems to more robust many-body quantum simulators. Weak measurement enables an observer to extract some information about a quantum system while only partially disturbing it, but there is little understanding of how this process affects ultracold atomic systems with their own internal dynamics. Furthermore, feedback control has scarcely been implemented in the many-particle context. This proposal theoretically investigates ‘quantum state control’ protocols for ultracold atoms, starting with spinor Bose-Einstein condensates (BEC) and extending to systems beyond mean-field theory. Ultracold atoms are an ideal platform for this research because they are highly controllable and well suited to weak measurement and feedback control. Incorporating measurement and feedback into the quantum control theory toolbox for ultracold atomic systems would be a transformative advance forward in AMO theory. The project extends theoretical work by the PI via three research aims: (1) to demonstrate dynamical creation of new magnetic phenomena in spinor BECs, (2) to extend quantum feedback control beyond mean-field to fermionic lattice systems, and (3) to study the potential of weak measurement and feedback for entanglement generation. Each aim focuses on a different one-dimensional physical system united by a common theoretical framework for quantum control in ultracold atomic systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.